I spent _WAAAAAYYYYYYY_ too long trying to write a test for a function that probably didn't even need to be tested in the first place and probably the test provides ~0 value but I did it you guys! I got it working!
Also I published v0.2.0 of clockabilly, which is my Rust library that lets you mock out time and sleeping and stuff -- now you can (pretend to) sleep and then execute a callback when you (pretend to) wake up.